The use of intravascular catheters has become an effective method for treating many types of vascular disease. In general, an intravascular catheter is inserted into the vascular system of the patient and navigated through the vasculature to a desired target site. Using this method, virtually any target site in the patient's vascular system may be accessed, including the coronary, cerebral, and peripheral vasculature. Examples of therapeutic purposes for intravascular catheters include percutaneous transluminal angioplasty (PTA) and percutaneous transluminal coronary angioplasty (PTCA).
Intravascular catheters are commonly used in conjunction with a guidewire. A guidewire may be advanced through the patient's vasculature until it has reached a target location. Once in place, a catheter may be threaded onto the guidewire and urged distally until the distal end of the catheter reaches a target location.
When in use, the guidewire enters the patient's vasculature at a convenient location and then is urged to a target region. The path taken by a catheter through the vascular system is often tortuous, requiring the guidewire to change direction frequently. In order for the guidewire to conform to a patient's tortuous vascular system, it is desirable that it be very flexible, particularly near the distal end.
The guidewire will often confront a stenosis when passing through the vasculature. In addition, the stenosis may completely block the vessel as is the case with a chronic total occlusion. The success of the procedure often depends on the ability to insert the guidewire through the chronic total occlusion.